What are the working principles and applications of external thermopile sensors?
Infrared thermopile sensor Thermopile, also known as thermopile, is a kind of temperature sensor. When the external radiant energy shines on the thermopile, a temperature gradient is generated in it, and a potential difference is generated at both ends. If they are formed into a loop, current will flow. The main technical properties of thermopile include direct sensitivity, internal resistance, time constant, and acceptance area.
Thermopile, also known as thermopile, is a temperature sensor. When the external radiant energy shines on the thermopile, a temperature gradient is generated in it, and a potential difference is generated at both ends. If they are formed into a loop, current will flow. The main technical properties of thermopile include direct sensitivity, internal resistance, time constant, and acceptance area.
There are two types of thermopile structures: one uses metal wires as effective devices, such as imprint bismuth, manganese, and copper-nickel alloys; the other uses vacuum deposition lithography to make two kinds of metal or semiconductor materials.
The thermopile has excellent uniform sensitivity in a longer wavelength range. Different window materials are usually used to obtain the long-wave limit. Therefore, the window materials should be paid attention to when using, such as glass, quartz, calcium fluoride, sodium chloride, iodine bromide, cesium iodide, thallium bromide iodide, etc. When using, the window material should be prevented from deliquescing and the working environment should be dry.
Thermopile is mainly used to detect the power of light radiation, as the receiving element of infrared spectrophotometer and monochromator, and can also be used as a comparison standard for radiometric measurement, calibrating various light sources, and measuring the spectral sensitivity and integral sensitivity of other infrared photoelectric elements.
Infrared thermopile sensor working principle
The absorbing film irradiated by infrared rays is a thin film with small heat capacity and easy temperature rise. The lower part of the liner is a hollow structure. The design of this structure ensures the temperature difference between the cold end and the temperature measurement end. The thermocouple is composed of polysilicon and aluminum, which are connected in series. When the temperature of each thermocouple temperature measurement terminal rises, the thermoelectromotive force Vn will be generated between the thermocouples, so the sum of their voltages can be obtained at the output terminal.
Thermopile infrared temperature sensor
The thermopile infrared temperature measurement sensor directly induces thermal radiation [3], which provides a perfect solution for non-contact temperature measurement. Its innovative silicon-based micromechanical technology ensures its excellent long-term stability and very low temperature Sensitivity coefficient, excellent photoelectric characteristics. The thermopile infrared sensor makes the non-contact temperature measurement system have a very low price. It does not require cooling, but can achieve an accuracy of ±1°C over the entire temperature measurement range. For a relatively narrow temperature measurement range, such as body temperature measurement, the accuracy can reach ±0.1°C.
Application of infrared thermopile sensor in non-contact thermometer
Use a high-precision thermistor to measure the ambient temperature of the thermopile, and then the CPU calculates the measured temperature. Some standard temperature conditions can be pre-written in the EEPROM, for example: the output voltage measured under the condition that the temperature of the measured object is 37°C and the ambient temperature of the thermopile is 25°C. Moreover, the output voltage of the thermopile, the bias of the op amp and the discreteness of the gain, etc. can also be corrected by software.
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